Printing method utilizing electrolysis



United States Patent M 3 492,206 PRINTING METHOD UTILIZING ELECTROLYSIS Satoru Honjo, 105 Mizonuma, Oaza, Asaka-cho, Kita-Adachigun, Saitama, Japan No Drawing. Filed Aug. 4, 1966, Ser. No. 570,149 Claims priority, application Japan, Aug. 4, 1965, 40/47,046 Int. Cl. B41m 5/00; C23b 7/08 US. Cl. 204- 4 Claims ABSTRACT OF THE DISCLOSURE A printing method comprising providing an electrically conductive material coated with a layer of stripping material selectively removing the coating layer in accordance with an image to be reproduced, subjecting the exposed portions of the electrically conductive material to electrolysis or electrophoresis to form a deposit thereon and transferring the deposit to a transfer surface to obtain a copy.

This invention relates to a new printing method. Ordinarily printing is by a method employing a printing ink, and a printing machine. Because of the complicated printing mechanisms necessary however, highly skilled techniques are required for the printing operation. It is unavoidable when employing this method that workers hands were readily smeared and clothes often ruined. Of late, simple offset printers overcoming these disadvantages have been marketed but there still appears to be much more room for improvement in methods of printing.

Mimeographs have also been employed for a long time as a simplified printing means but the quality of images obtained thereby are inferior when compared with that of a relief or flat plate, and the apparatus for making stencils is rather expensive.

In the spirit printing method, not employing ink, the number that can be printed is small and instead of a deep black image, a blue-violet one is obtained.

Further, there has also been developed the electrostatic printing method wherein electrostatic latent images are formed and a powdered ink (toner) is caused to adhere thereto. This method is not the best however, since additional complicated developing means and latent image forming means are necessary.

An important object of this invention is to provide an improved printing method wherein the number of prints or copies made is large and the image forming material can be selected from a wide range.

Another object of this invention is to provide a printing method requiring no skill on the part of the operator in the printing operation.

The present invention is concerned with the printing method of forming images by depositing particles utilizing a phenomena such as electrolysis or electrophoresis on an electrode or utilizing a color forming phenomenon accompanying the oxidation-reaction. That is to say, the invention is characterized by coating a thin layer of a metal or a material sufficiently electrically conductive mounted continuously on a substrate support with a suitable material, eliminating the coated layer in accordance with an image to be reproduced by a suitable optical or mechanical means and thereby exposing the electric con- 3,492,206 Patented Jan. 27, 1970 ductive layer on that part to prepare a printing original and subjecting it to electrolysis to obtain two or more copy prints.

Included in the coating layer of my invention are the following methods, however, other methods common thereto fundamentally may also be employed.

1. A light hardenable resin layer When a part exposed to light is hardened and made insoluble by a solvent, the coated layer is Washed with the solvent and the unexposed part is dissolved as the electrically conductive layer on a base plate is exposed. Illustrative of this resin layer are gelatin and polyvinyl alcohol containing bichromate, these consisting essentially of polyvinyl cinnamate, as well as others containing light hardenable diazo compounds. A method of utilizing a tanning development of a silver salt light-sensitive layer in combination may also be employed.

II. A pressure sensitive stripping layer This is a layer capable of being damaged and stripped from a base by pressing or capable of being strongly adhesive and removed to a transfer material to expose the base by pressing. Illustrative of this type is a layer containing pressure sensitive and breakable capsules and illustrative of that are brushed resin layers and Wax layers used in tachometers for automobiles or carbon papers.

III. A heat sensitive stripping layer This is a layer having a suitable heat softening temperature and capable of being transferred to a transfer material in contact therewith in those parts that are heated to a temperature higher than the remainder of the ma terial. This recording material is placed upon an original and subjected to reflection or image through exposure, for example, by the Thermofax process of the Minnesota Mining and Manufacturing Company.

IV. Others Considering the case where a recording material is scanned by a mechanism whereby a high intensity light such as a laser light is modulated in accordance with an original record, it is apparent that such a coating layer which decomposes and evaporates selectively according to the intensities of the light may be adapted to this invention. In that case, it is preferred that the coating be so composed that the laser light may be effectively absorbed thereby and its lower electrically conductive layer is so composed that the laser light may be readily reflected or permeated. Since a thin metal coating is not deteriorated in a short time by radiation of the laser light unless it is too thin, in general, no special working is necessary therefor. An insulating layer may be suitably colored. An electrically conductive layer may be of a thin metal layer or metal plate or in some cases, carbon black or a finely divided metal dispersed in a suitable binding agent. It may contain a hydroscopic inorganic salt, organic compound-polyhydric alcohol mainly or an electrolyte. Typical or a support are paper and plastics. As the adhesion of a metal layer and insulating layer vary with the variety of the combination thereof, a sub-layer having no influence upon the conductivity may be provided when the adhesion is bad. A thin film of polyamide resin, linear polyester resin or maleic acid copolymer may be used therefor.

If the adhesion is not sufiicient in the case of a pressure sensitive stripping layer, the stripping extends to the surrounding part to thereby result in a lowering of the image quality. Accordingly a tight adhesion of the metal layer and the insulating layer is very important from this point of view. A pressure sensitive adhesive layer may be used in place of a pressure sensitive layer in order to strip only the image part.

Since one of the principal features of the invention is the obtaining of a multiplicity of copies, the final image is formed on another transfer material, Therefore, in obtaining an electrically conductive image by light hardening for example, a left-right reverse image is formed on the master. When using a pressure sensitive layer, a writing pressure or type pressure is preferably applied from the side of the support. If so, the electrically conductive image is left-right reverse and the normal image is obtained on the transfer material. When the transfer material is transparent, there is no such restriction as described above and furthermore, the writing may be done on the side of the recording layer.

It is preferred that the material formed on the image part by electrolysis may be so as to be transferred readily to a transfer material. In general, material deposited on metal surfaces is transferred to others relatively easily, but the transferring may be diflicult sometimes due to the fact that the metal surface has an affinity for fine particles that the image consists of. In that case, a layer is provided to ease the transfer of the deposited image to such an extent that the passage of electric current is not hindered. For example, a thin layer of silicone type releasing layer is applied to the surface carrying an electrically conductive image, or a silicone oil is applied by spraying.

The electrolytic development is carried out by the procedures that follow.

Aqueous solutions containing silver nitrate, nickel chloride, copper sulfate, etc., are typical of a solution containing a suitable electrolyte and a metal ion of noble oxidation-reduction potential. In the electrolysis, the conductive area of a recording layer acts as a negative pole and silver or nickel is obtained.

Illustrative of a material depositing an image are lead thiosulfate, antimony chloride, antimony oxysulfate and potassium antimonate. In this case also, the side of the recording layer acts as the negative electrode.

Coloring matters or other image forming materials can also be obtained by utilizing the changes of pH accompanying the electrolysis. For example, a solution containing a diazo compound and material capable of coupling is coupled by raising the pH near a negative electrode. Moreover, a hydroxide may be precipitated at a negative electrode by incorporating into said solution a Water soluble metal salt whose hydroxide is water insoluble.

Using the ammonium compound, an image consisting of carbon black can be made. For example, when carbon black is dispersed in a resin that is water soluble when acid, it becomes water insoluble with an increase in the pH and the resin is made insoluble by the negative electrode. The carbon black is then precipitated simultaneously to form a black image. If a white pigment is used in place of carbon black in another embodiment, the image is obtained on black transfer paper. Illustrative of this is a polyamide resin having a high amine value.

The metal of an electrode may also participate in the reaction. The reaction of iron ion with pyrogallol or pyrocatechnic acid has been famous from olden times and using this reaction, a blue-black image is obtained. At this time, iron ion is given by oxidation at an electrode. In this case however, the number to be printed is restricted by the consumption of the electrode.

The condition for electrolysis is adjusted by thecomposition of the electrolyte or the kind of an electrolytic reaction within such a range so that the insulating layer on a non-image part is not broken. It has been found,

however, that when the electric current is concentrated, a highly electric conductive image is formed and little, if any, break in the insulation occurs in the background and thus printing is possible several tens of times.

EXAMPLE 1 The following composition was charged to a porcelain ball mill and blended to give a uniform mixture.

Parts by weight Zinc stearate powder Polyamide resin Versamid 100 (by General Mills Co.) 15 Epoxy resin Epon 1007 (Shell Chemical Co.) 15 Butanol 40 Methyl ethyl ketone 40 Toluene 20 An aluminum foil was laminated on one side of a soft white paper and this solution was applied to the side of the foil to be 10 microns in thickness when dry. After drying, the coated laminate was allowed to stand at room temperature for two days to harden the resin completely. When writing pressure was applied to the layer from the side of the paper, the pressed layer was stripped to expose the metal surface. The thus processed foil, used as a master, was subjected to development in an electrolyte obtained by dissolving 2 parts of a polyamide resin, Versamid 100 in 100 ml. of aqueous acetic acid solution, adjusting the pH to 6-7 and dispersing carbon black uniformly therein.

When the aluminum foil of the recording paper was connected to a negative electrode, a Pt-electrode was immersed in the electrolyte as a positive electrode, and a DC voltage of 4 v. was applied thereto, a black image appeared on the exposed metal area. Before drying of the image, a paper for transferring the image was pressed in contact with the laminate to transfer the carbon image. The electrolysis was carried out again and again to prepare the original for printing further copies. Twenty good copies were obtained.

EXAMPLE 2 Parts Butadiene-styrene copolymer resin Pliolite S-SD-.. 6 Barium stearate 40 Tricresyl phosphate Q. 0.2 Castor oil 10 Toluene 100 On the other hand, an imitation paper having a thickness of 40 microns was provided the one side of which was coated with an adhesive layer of 2 microns in thickness consisting of 10 parts of chlorinated rubber, 7 parts of castor oil and 10 parts of titanium oxide.

When the thus coated surface was placed upon the pressure sensitive layer and a writing pressure was applied from the back of the material carrying the pressure sensitive layer, the pressure sensitive layer adhered to the adhesive layer and the carbon layer was exposed.

Twenty copies were obtained by an electrolysis similar to Example 1.

EXAMPLE 3 An original paper was prepared by laminating a thin layer of aluminum on one side of imitation paper of 40 microns in thickness. Firstly, a partially saponified polyvinyl acetate was applied to the surface of aluminum to give a thickness of about 0.5 micron and then a lightsensitive resin, Kodak Photo Resist manufactured by Eastman Kodak Co. of Rochester, N.Y., was applied thereto to be 2 microns in thickness on a dry base in a dark place. After drying, the paper was tightly adhered to a positive original, exposed to ultraviolet ray and surface treated with trichlene. Since there did not occur the light hardening on the image area, the area was dissolved in trichlene to expose the aluminum.

It was then dried and coated thinly and uniformly with a silicone oil, polymethylsiloxane by spraying to ease the transferring of an image to be formed. It was immersed in an electrolyte having the following composition for electrolysis:

. Parts p-Aminodiethylaniline hydrochloride 4.4 p-Aminodimethylaniline hydrochloride 1.9 Tartaric acid 6.22 Sodium nitrite 2.07 Fluoroglusynol 0.042 5 ,7-disulfonyl-s-aminonaphthol 2. 39 Salt 58.47

Water to make 1000 ml. of solution.

When the electrolysis was carried out by the use of the aluminum foil as a cathode and a Pt-electrode as an anode, a brown azo-coupled product was deposited on the aluminum part, which was then transferred to another transfer material. Thirty good prints were obtained by repeating these steps.

What is claimed is:

1. A method of printing comprising providing a continuous electrically insulating, strippable coating layer on an electrically continuous, conductive base, selectively removing said coating layer in accordance with an image to be reproduced by subjecting said coating layer to the action of either heat or pressure, thereby selectively exposing said electrically conductive base, connecting said base to the electrode of an electrolysis or electrophoresis bath until there is a deposit on said base and then transferring said deposit to a transfer surface.

2. A method of printing as set forth in claim 1 wherein said insulating coating layer is a pressure sensitive stripping material and is removed from said electrically continuous, conductive base by applying local pressure thereto from the other side of said base.

3. A method of printing as set forth in claim 1 wherein said insulating coating layer is a pressure sensitive stripping material, wherein there is additionally provided a receiving sheet coated with an adhesive layer, and wherein said insulating coating layer is removed from said electrically continuous, conductive base by applying local pressure thereto from the other side of said base while said insulating coating layer and said adhesive layer are in contact, whereby said insulating coating layer is selectively transferred to said adhesive layer.

4. A method of printing as set forth in claim 1 wherein said insulating coating layer is a heat sensitive stripping material and is removed from said electrically continu ous, conductive base by applying heat through an appropriate mask to cause the coating to selectively soften, which softened coating is then removed in accordance with the form of image to be reproduced, thus exposing said electrically conductive base.

References Cited UNITED STATES PATENTS 1,963,834 6/1934 Decker 20418 2,306,082 12/1942 Prest 204--18 2,874,085 2/1959 Brietzke 2048 3,037,923 6/1962 Gnau 204181 3,152,969 10/1964 Eastman 204l7 J. H. MACK, Primary Examiner T. TUFARIELLO, Assistant Examiner U.S. Cl. X.R. 

